This application bases priority on German Application No. DE 103 02 251.1, filed Jan. 22, 2003.
1. Field of the Invention
The invention relates to a flow sensor with a tube through which the medium to be measured flows and a housing comprising a lower shell and an upper shell and receiving measuring electronics with unions provided with a flow bore communicating with the tube and which are received in recesses made in facing sides of the lower and upper shells.
2. Description of the Prior Art
Numerous different designs of such flow sensors are known. DE 100 62 609 A1 discloses a flow sensor having the features described above. In the case of said flow sensor, the unions are constructed in one piece with the tube, which can be disadvantageous for certain applications because mechanical stresses, which can emanate from the housing or the unions, are transmitted to the tube.
The problem of the invention is to provide a flow sensor, in which mechanical stresses emanating from the housing or unions are not transmittable to the tube.
According to the invention, this problem is solved in that the union has an outer part, an inner part and a central piece, the inner part of both unions is provided with a blind hole concentric to the flow bore and in which are elastically mounted the ends of the tube, and the central piece is constructed cylindrically with a reduced diameter compared with the parts of the union and the lower shell and the upper shell are in each case provided with a semicylindrical portion receiving the central piece of the union.
One of the parts of the unions, and the areas of the facing sides of the lower and upper shells receiving the same, must not have a cylindrical construction.
Preferably the ends of the tube are mounted in the inner part of each of the unions by at least one first O-ring, sealing against the tube, located in a circumferential groove in the wall of the bore.
A preferred embodiment is characterized by at least one second O-ring, sealing against the central piece of the union made in the portion of the recesses receiving the central pieces of the unions.
The unions can be made from a plastics material and the inner part of the unions can, in each case, be embraced by a shape-stabilizing metal ring. A pin used to prevent turning and engaging in the wall of the lower shell or upper shell can be guided through the inner part of the unions.